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The degradation dynamics of polyhydroxyalkanoates of different composition has been studied in an eutrophic storage reservoir for two seasons. It has been shown that the biodegradation of polymers under natural conditions depends not only on their structure and physicochemical properties but also, to a great extent, on a complex of weather-climatic conditions affecting the state of the reservoir ecosystem. The molecular genetic analysis of 16S rRNA has revealed bacterial species (clones) probably involved in the degradation of polyhydroxyalkanoates in a model storage reservoir. 相似文献
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The content of beta-endorphin, methionine- and leucine-enkephalins was determined in the brain and blood of albino mongrel rats. The unified scheme is suggested for releasing opioid neuropeptides from the brain tissue and blood. 相似文献
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Sushchik N. N. Kalacheva G. S. Zhila N. O. Gladyshev M. I. Volova T. G. 《Russian Journal of Plant Physiology》2003,50(3):374-380
The effect of ambient temperature on the composition of intracellular fatty acids and the release of free fatty acids (FFA) into a medium by cyanobacterium Spirulina platensis and eukaryotic microalgae, Chlorella vulgaris and Botryococcus braunii, was studied using their batch cultures. It was found that all the species studied, regardless of their taxonomic status, responded to the temperature regime by similar changes in their intracellular fatty acid composition: the relative content of more unsaturated fatty acids decreased with the elevation of temperature. At the same time, in the prokaryote, this temperature shift blocked, first of all, the elongation of 16:0 to 18:0 and then their further desaturation. In eukaryotes, the change in the desaturation of dienoic to trienoic fatty acids was the most pronounced process. The ratio of dienoic to trienoic fatty acids remained almost unchanged in S. platensis. The relative content of extracellular unsaturated FFA increased in the prokaryotic organism S. platensis at a higher temperature. But no significant changes in the composition of extracellular unsaturated FFA were detected in eukaryotic algae upon temperature elevation. 相似文献
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MARIE‐NOËLLE VAULTIER MARIE‐PAULE HASENFRATZ‐SAUDER DIDIER LE THIEC PIERRE DIZENGREMEL GRAHAM NOCTOR YVES JOLIVET 《Plant, cell & environment》2013,36(11):1981-1991
Oxidative stress caused by ozone (O3) affects plant development, but the roles of specific redox‐homeostatic enzymes in O3 responses are still unclear. While growth day length may affect oxidative stress outcomes, the potential influence of day length context on equal‐time exposures to O3 is not known. In Arabidopsis Col‐0, day length affected the outcome of O3 exposure. In short‐days (SD), few lesions were elicited by treatments that caused extensive lesions in long days (LD). Lesion formation was not associated with significant perturbation of glutathione, ascorbate, NADP(H) or NAD(H). To investigate roles of two genes potentially underpinning this redox stability, O3 responses of mutants for cytosolic NADP‐isocitrate dehydrogenase (icdh) and glutathione reductase 1 (gr1) were analysed. Loss of ICDH function did not affect O3‐induced lesions, but slightly increased glutathione oxidation, induction of other cytosolic NADPH‐producing enzymes and pathogenesis‐related gene 1 (PR1). In gr1, O3‐triggered lesions, salicylic acid accumulation, and induction of PR1 were all decreased relative to Col‐0 despite enhanced accumulation of glutathione. Thus, even at identical irradiance and equal‐time exposures, day length strongly influences phenotypes triggered by oxidants of atmospheric origin, while in addition to its antioxidant function, the GR‐glutathione system seems to play novel signalling roles during O3 exposure. 相似文献
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On the effect of ammonium and lithium ions upon frog nerve deprived of sodium 总被引:3,自引:0,他引:3 下载免费PDF全文
An analysis has been made of the effect of ammonium and of lithium ions upon frog nerve deprived of sodium. Ammonium ions cannot substitute for sodium ions and restore the excitability of the nerve fibers; nor can they increase the L fraction of the membrane potential and the efficiency of the nerve reaction. Certain observations, however, indicate that the presence of ammonium ions outside the nerve fibers may delay the development of inexcitability in a sodium-free medium of nerve fibers restored by a moderate amount of sodium ions. Lithium ions can substitute for sodium and restore to nerve fibers of the A and C groups the ability to conduct impulses; the effect upon B fibers has not been investigated. Lithium cannot substitute for sodium in the role that sodium plays in the creation of the L fraction and in the establishment of the nerve reaction. In this respect lithium and sodium have opposite effects. This fact establishes an important difference between the two physiological responses that the nerve fibers can produce, the nerve impulse and the nerve reaction. With untreated nerve the depolarization of nerve by lithium ions at high concentrations is preceded by a phase of hyperpolarization; with nerve deprived of sodium the depolarization begins without delay. 相似文献
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GUILLERMO H. CASSINI MANUEL MENDOZA SERGIO F. VIZCAÍNO M. SUSANA BARGO 《Lethaia: An International Journal of Palaeontology and Stratigraphy》2011,44(2):153-165
Cassini, G.H., Mendoza, M., Vizcaíno, S.F. & Bargo, M.S. 2011: Inferring habitat and feeding behaviour of early Miocene notoungulates from Patagonia. Lethaia, Vol. 44, pp. 153–165. Notoungulates, native fossil mammals of South America, have been usually studied from a taxonomic point of view, whereas their palaeobiology has been largely neglected. For example, morpho‐functional or eco‐morphological approaches have not been rigorously applied to the masticatory apparatus to propose hypothesis on dietary habits. In this study, we generate inferences about habitat and feeding preferences in five Santacrucian genera of notoungulates of the orders Typotheria and Toxodontia using novel computer techniques of knowledge discovery. The Santacrucian (Santa Cruz Formation, late‐early Miocene) fauna is particularly appropriate for this kind of studies due to its taxonomic richness, diversity, amount of specimens recorded and the quality of preservation. Over 100 extant species of ungulates, distributed among 13 families of artiodactyls and perissodactyls, were used as reference samples to reveal the relationships between craniodental morphology and ecological patterns. The results suggest that all Santacrucian notoungulates present morphologies characteristic of open habitats’ extant ungulates. Although the Toxodontia exhibits the same morphological pattern of living mixed‐feeders and grazers, the Typotheria shows exaggerated traits of specialized grazer ungulates. □Craniodental morphology, ecomorphology, fossil ungulates, knowledge discovery, South America. 相似文献